26. Arthropods (fleas, part 2) Flashcards
do fleas have wings?
no
what shape are fleas?
oval
what is specially adapted in fleas?
the hind legs to enable them to jump long distances
what is morphologically different about a fleas head?
it is disproportionally small
how many species of fleas exist?
over 2000
in which direction are fleas bodies compressed? why is this helpful?
laterally, so they may move through the feathers and hairs on the hosts body
what are fleas mouthparts adapted for?
piercing skin and sucking blood
what do fleas require?
a blood meal
what color are fleas?
light to deep brown in color
why are fleas of clinical significance to humans?
because they are vectors for many other diseases
what kind of infections do fleas transmit to humans and other animals?
- bacterial
- viral
- protozoan
- helminth
what are examples of the bacterial infections transmitted by fleas?
Fleas have helped cause epidemics by transmitting the bubonic plague between rodents and humans by carrying Yersinia pestis bacteria
what are examples of the protozoan infections transmitted by fleas?
Trypanosome protozoans such as those of the subgenus Herpetosoma, use a variety of flea species as vectors
what are examples of the helminth infections transmitted by fleas?
fleas are intermediate hosts for tapeworms, including the cestodes Hymenolepis and Dipylidium
what are the life cycle steps of fleas?
- eggs
- larvae
- pupae
- adults
who sheds the flea eggs into the environment? (male/female)
the female
do fleas multiply rapidly or slowly?
rapidly
what are the four main species of fleas that infest humans?
- Cat flea (Ctenocephalides felis)
- Dog flea (Ctenocephalides canis)
- Human flea (Pulex irritans)
- Oriental rat flea (Xenopsylla cheopis)
why are Ctenocephalides spp. of medical importance?
they are vectors of rickettsial diseases - example Rickettsia typhi
what are the three groups that Rickettsia is classified into?
- spotted fever
- typhus
- scrub typhus
what can Ctenocephalides spp. serve as an intermediate host for?
tape worms, including Hymenolepis and Dipyladum
what are morphological characteristics of Ctenocephalides felis?
Similar to the dog flea, except:
- head is elongated,
- front comb (ctenidia) is almost as long as the rest of the combs.
what are morphological characteristics of Ctenocephalides canis?
Similar to the cat flea, except:
- head is strongly rounded,
- front comb (ctenidia) is half the size of the rest of the combs.
which species does the Pulex irritans infect?
humans
what is different about the head of the Pulex irritans flea of humans?
Head without ctenidia (i.e. comb structures).
Front head smoothly rounded.
is Pulex irritans an efficient vector of flea-borne diseases?
no, this species is not an efficient vector of any flea‐borne diseases, but its bite can cause allergic reactions due to salivary proteins
what is the vector of Yersinia pestis (bubonic plague)?
Xenopsylla cheopis
in North America, what us the cycle of plague?
Xenopsylla cheopis and prairie dogs
what is a form of typhus transmitted by Xenopsylla cheopis?
Murine typhus, also called endemic typhus
what organism is Murine typhus in contrast to? what is that transmitted by?
epidemic typhus, which is transmitted by lice
what is the rat flea?
Xenopsylla cheopis
what is characteristic about the head of the rat flea?
Head without ctenidia (i.e. comb structures)
Front head rounded
how can the itching assiciated with flea bites be treated?
with anti-itch creams, such as antihistamines or hydrocortisone
what is critical to flea survival?
humidity
why is humidity key to flea survival?
eggs need relative humidity of at least 70–75% to hatch, and larvae need at least 50% humidity to survive
what temperatures are characteristic for flea life?
- fleas thrive at higher temperatures, but need 21°to 32°C to survive.
- lower temperatures slow down or completely interrupt the flea life cycle
what would interrupt the flea life cycle?
Using dehumidifiers with air conditioning and vacuuming will interrupt the flea life cycle
